KARACHI: The Federal Board of Revenue has estimated Rs20 billion monthly losses in revenue collection due to significant reduction in sales tax rates on petroleum products applicable during June 2018, officials said on Tuesday.The government has adjusted the rise in international oil prices by reducing sales tax rates instead of passing it on to the consumers for the month of June 2018.The Pakistan Muslim League-Nawaz government which concluded its five year tenure on May 31, 2018,decided not...